The article is a case report of an unusual manifestation of primary hyperparathyroidism seen in the mandible. Primary hyperparathyroidism is a rare disorder that can present its first symptoms in the jaws. The pre- and post-treatment radiographic features of such cases have only rarely been reported in dental literature. This case report highlights the importance of careful clinical and radiographic examination before commencing root canal treatment.

Primary hyperparathyroidism is a relatively rare disorder in which the parathyroid glands secrete excessive amounts of parathyroid hormone (PTH). Increased activity of these endocrine glands could be due to an adenoma in one or more of the four parathyroid glands, hyperplasia of the parathyroid tissue, or carcinoma of the parathyroid.

Hyperparathyroidism has a higher prevalence in women, the female: male ratio being 3:1. It usually affects middle-aged persons. A pathologic fracture may be the first symptom of the disease. Bone pain and joint stiffness may be present. Renal calculi are a common finding in this condition. Occasionally, the first sign of the disease may be a cyst in the jaw.[1] The disease should be considered by the dentist whenever single or multiple radiolucencies are observed on radiography of the jaw. A history of recurrent osseous or soft tissue lesions is suggestive of this disorder.[2] Almost all patients with hyperparathyroidism have skeletal lesions in the advanced stages. The loss of calcium and phosphorus in this condition results in generalized osteoporosis. Malocclusion due to drifting of teeth, with definite spacing of the teeth, may be one of the first signs of the disease.

The roentgenographic features (in the jaws) of the disease include generalized radiolucency as compared with those of normal people. Oval or round radiolucent areas, which may be lobulated, could be present. Cystic lesions may be seen in the jaws. The radiograph is typically described as having a 'ground glass' appearance. The lamina dura around the teeth may be partially lost. Serum calcium will be elevated above the normal level of 9-12 mg/dl. Treatment involves excision of the parathyroid tumor. Surgical excision usually makes all the parameters to revert to normal.

Although our search of the literature revealed some case reports of cystic lesions in the jaws of hyperparathyroid patients, we did not come across any report of the roentgenographic appearance of a treated case. We therefore present a case report of a hyperparathyroid patient in whom the postoperative radiograph showed total disappearance of a cyst in the mandible.

This article highlights the importance of making a firm diagnosis before embarking on endodontic therapy. The finding of a periapical radiolucency on a radiograph should not automatically lead to access opening and root canal therapy by the dentist. In this article we describe how a periapical radiolucency due to non-odontogenic reasons resolved after appropriate medical treatment.

Case Report

A 42-year-old female patient reported to a private practice at Chennai, India, with complaints of recurrent pain and swelling of the right side of the lower jaw. The patient had no history of diabetes mellitus, hypertension, or any other relevant systemic disease. She gave no history of any familial diseases. However, on questioning she reported having recurrent vomiting, loss of appetite, tiredness, weight loss, and joint stiffness for the past 3 months.

Intraoral examination revealed a swelling obliterating the right buccal vestibule of the mandible, with a shallow silver amalgam restoration in relation to the right mandibular first molar. We advised an intraoral periapical radiograph and an orthopantomograph (OPG) before any further treatment. The OPG revealed a periapical radiolucency in relation to the lower right mandibular second premolar and first molar [Figure 1]. The radiographic findings revealed that the restoration in the mandibular first molar did not involve the pulp. The results of sensitivity tests (electric pulp and thermal tests) on the right mandibular first and second molars were positive. apart from this the teeth also showed some other incipient carious lesions.

We decided to take a biopsy of the cystic lesion before arriving at a final diagnosis. Before undertaking any procedure at the dental clinic, we referred the patient to a physician for an opinion regarding her general symptoms. Meanwhile, she was advised analgesics for symptomatic relief.

The patient consulted a general physician the very next day. Investigations revealed anemia, elevated serum calcium of 14 mg/dl (normal range 9-11 mg/dl), and low serum phosphorus (2 mg/dl; reference range: 2.4-5 mg/dl). Serum PTH was markedly elevated at 845.6 pg/ml (normal range 15-65 pg/ml). Serum alkaline phosphatase was also markedly elevated at 1579 IU/l (normal range 500-750 IU/l), with a predominant increase in the bone fraction. The investigation results were suggestive of hyperparathyroidism and so an endocrinologist's opinion was sought. The patient was further investigated. The thyroid profile appeared normal. Whole-body scan revealed features of metabolic bone disease. In view of her complaints of recurrent vomiting, a gastroenterologist's opinion was also obtained. Upper gastrointestinal endoscopy and barium swallow were performed and were normal. Ultrasound examination of the abdomen revealed mild hepatomegaly. CT chest was normal. A parathyroid scan was done which revealed a parathyroid adenoma. The parathyroid adenoma was surgically excised, following which she became symptomatically better. She soon returned to good health and could resume her routine work.

The patient reported to us about 5 years after surgery. She was advised an OPG for evaluation of the periapical radiolucency that had been detected at her first visit. The radiograph revealed that the cystic lesion had disappeared altogether [Figure 2], suggesting that the lesion was a manifestation of the hyperparathyroidism she had at her first visit to us.

Discussion

Primary hyperparathyroidism is a disorder of mineral and bone metabolism that is caused by increased secretion of PTH by the parathyroid glands. In most cases, primary hyperparathyroidism is associated with a hyperfunctioning adenoma of a single parathyroid gland. In unusual cases, primary hyperparathyroidism can result from parathyroid carcinoma and in certain cases it can be associated with diffuse hyperplasia of all four glands. In patients with parathyroid hyperplasia, the condition is sometimes familial and may be part of the syndrome of multiple endocrine neoplasia (MEN). Secondary hyperparathyroidism develops in response to chronic hypocalcemia, as occurs in chronic renal disease, calcium malabsorption, or vitamin D deficiency.[3]

Elevated PTH levels act directly on bone and kidney and indirectly on the intestine to cause hypercalcemia. The classical clinical features of patients with primary hyperparathyroidism are 'stones, bones, and groans.' The renal symptoms consist of recurrent episodes of low back pain, hematuria, and passage of stones in the urine. The bone symptoms include pain and tenderness in areas of increased turnover, pathologic fractures due to bone cysts, or the symptoms of osteoporosis. The groans refer to symptoms resulting from hypercalcemia, which include polyuria, polydipsia, anorexia, constipation, abdominal pain, pruritis, headache, weakness, fatiguability, emotional lability, and loss of mental acuity.

Almost all cases of hyperparathyroidism have skeletal lesions, some of which could occur in the skull or jaws. The loss of phosphorus and calcium in this condition results in generalized osteoporosis which, left untreated, results in abortive attempts at repair and new bone formation. The new bone may be resorbed, and the resorption may lead eventually to pseudocyst formation in untreated cases. The periapical radiolucency can be easily mistaken for a periapical infection. This case is an excellent example of a periapical radiolucency that does not call for root canal treatment. Hence, every practicing dentist needs to have a good knowledge of medical conditions and must develop the habit of taking a thorough medical history in every case.

The case report presented in this article shows radiographic changes associated with pre-treatment and post-treatment of primary hyperparathyroidism, as seen in the mandible; a rare documentation in dental literature.[4],[5]